How to fix final render causing issue by having pixelation using cycles?
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This looks like an issue known as Z-fighting. What that means is you have some geometry that is very close together, so close that the camera doesn't know which one is on top, thus you get a mix of both.

From your images it looks like there is a blue shell that overlays the white body of the controller.

To fix this, a possible option is to remove the part of the white body that is under the blue shell. This will get rid of the geometry that is too close, and also make it faster to render since there will be less geometry.

Another possible (and much easier) option to try is changing the Clipping settings in Camera tab of the Properties Panel on the right. Try increasing the start value (to something like 1) or decreasing the end values (to something like 30-50). Typically adjusting the start value will be more effective.